Plasma Epstein-Barr Virus DNA Load After Induction Chemotherapy Predicts Outcome in Locoregionally Advanced Nasopharyngeal Carcinoma

To investigate whether plasma Epstein-Barr virus (EBV) DNA load at induction chemotherapy (ICT) completion (postICT-DNA) is a useful outcome predictor in locoregionally advanced nasopharyngeal carcinoma (NPC) and to compare the prognostic value of postICT- DNA and post-chemoradiation therapy (CCRT) DNA (postRT-DNA).We retrospectively reviewed 278 patients with stage III-IV NPC treated with ICT followed by concurrent CCRT. The EBV DNA load was measured by quantitative polymerase chain reaction pre-ICT (pre-DNA), at ICT completion (postICT-DNA), and 1 week after CCRT completion (postRT-DNA).PostICT-DNA was associated with significantly worse 3-year overall survival (86.4% vs. 93.4%, P = .023), distant metastasis-free survival (69.2% vs. 93.9%, P < .001), and disease-free survival (64.6% vs. 88.7%, P < .001) than was undetectable postICT-DNA. In multivariate analysis, postICT-DNA was an independent predictor of overall survival (hazard ratio [HR], 2.567; 95% confidence interval [CI], 1.104-5.967; P = .029), distant metastasis-free survival (HR, 5.618; 95% CI, 2.781-11.348; P < .001), and disease-free survival (HR, 3.672; 95% CI, 2.064-6.533; P < .001). The postICT-DNA and postRT-DNA areas under the curve were 0.584 and 0.561 (P < .001), respectively, for predicting 3-year death; 0.717 and 0.649 (P < .001), respectively, for predicting 3-year metastasis; and 0.659 and 0.602 (P < .001), respectively, for predicting 3-year disease failure.Plasma EBV DNA load at ICT completion is a powerful and earlier outcome predictor in locoregionally advanced NPC that would facilitate further risk stratification and early treatment modification.